1. Field of the Invention
The present invention relates to a vehicle control device, which is configured to support an operation of a driver so as to increase an electric power regeneration amount in a vehicle capable of generating a braking force by recovering electric power to an in-vehicle battery.
2. Description of the Related Art
For example, as proposed in International Patent WO2012/053106A1, there is known a drive support device, which is configured to set a target stop position for a vehicle and to issue an instruction to release an accelerator pedal so that the vehicle stops at the target stop position. Moreover, as proposed in Japanese Patent Application Laid-open No. 2015-19521, there is known a vehicle including a regenerative generator, which is configured to set such a deceleration start position as to increase an electric power regeneration amount to be recovered to a battery during deceleration travel up to a target stop position and to decelerate the vehicle at a high deceleration so that a driver can carry out an ecological drive.
There is an upper limit for a charge current that can be supplied to a battery, and hence, on the vehicle including the regenerative generator, a braking force that can be generated by the electric power regeneration is also limited. Upon an emergency braking operation, a required braking force temporarily exceeds the braking force that can be generated by the electric power regeneration, and hence an insufficient amount in the braking force is compensated by a hydraulic friction braking. Thus, a rotational energy of the wheels cannot be used effectively. Therefore, for the ecological drive, it is important not to carry out the emergency braking operation. In the vehicle proposed in Japanese Patent Application Laid-open No. 2015-19521, when the vehicle approaches the target stop position, the vehicle speed has already substantially decreased, and hence the driver does not need to depress a brake pedal hard before the target stop position. Thus, the emergency braking operation by the driver can be suppressed, and the power can thus be efficiently recovered to the battery, resulting in an increase in fuel consumption performance. The control of increasing the deceleration when the vehicle is decelerating up to the target stop position (increasing the regenerative braking force), thereby increasing the regenerative electric energy in this way, is referred to as regeneration enhancement control.
Incidentally, there is known a vehicle into which a tuck-in suppression control function is built. The tuck-in refers to a phenomenon in which, when an accelerator pedal is rapidly returned during a turn of the vehicle, the vehicle is sharply directed inward of the turn (toward a steering wheel steering direction) (that is, a turn radius of the vehicle decreases). The tuck-in is generated by a large engine braking force acting on the turning vehicle when the depression of the accelerator pedal is rapidly returned, thereby increasing ground loads on the front wheels, resulting in an increase in cornering forces of front wheels.
The tuck-in suppression control is control of suppressing this tuck-in. For example, a device proposed in Japanese Patent Application Laid-open No. 2006-281935 is configured to decrease a reduction amount of an engine torque as a grip state of the tires approaches a limit of turn performance when the driver carries out a return operation of the accelerator pedal, to thereby alleviate a deceleration at which the vehicle decelerates.
However, when the regeneration enhancement control function and the tuck-in suppression control function are built into the vehicle, the following problem arises.
For example, the tuck-in suppression control acts to decrease (alleviate) the deceleration of the vehicle, whereas the regenerative enhancement control acts to increase a regeneration braking force, to thereby increase the deceleration of the vehicle. Therefore, when the regeneration enhancement control is started while the tuck-in suppression control is being carried out, the regeneration enhancement control of increasing the deceleration of the vehicle acts against the tuck-in suppression control of decreasing the deceleration, and thus the tuck-in may not be appropriately suppressed.